Related Experiment Video
Updated: Jun 6, 2025

Measuring Sub-23 Nanometer Real Driving Particle Number Emissions Using the Portable DownToTen Sampling System
Published on: May 22, 2020
Comprehensive elemental and physical characterization of vehicle brake wear emissions from two different brake pads
Carsten Neukirchen1, Mohammad Reza Saraji-Bozorgzad2, Michael Mäder3
1University of the Bundeswehr Munich, Faculty for Mechanical Engineering, Institute of Chemistry and Environmental Engineering, Werner-Heisenberg-Weg 39, 85577 Neubiberg, Germany; Joint Mass Spectrometry Center at Chair of Analytical Chemistry, Institute of Chemistry, University of Rostock, Albert-Einstein-Strasse 27, 18059 Rostock, Germany.
Abstract:
Non-exhaust emissions have gained increasing attention during the last years, with the upcoming EURO 7 regulation defining maximum PM10 emission factors for tire and brake emissions for the first time. This study, therefore, focusses on broadening the knowledge on chemical composition and physical characteristics of brake dust to define emission factors for heavy metal and organic pollutants. Particles from two pads were analyzed utilizing the Worldwide Harmonised Light Vehicle Test Procedure (WLTP) brake cycle. Geometric mean diameters for both pads were found with a bimodal distribution in the ultrafine range. PM10 emission factors of 15.1 ± 0.1 mg/km and 16.3 ± 0.4 mg/km were measured, which is 2.15 and 2.32 times higher than upcoming maximum permitted emission factor of 7 mg/km. On average 54.9 % and 58.1 % of PM10 was emitted as iron, with a wide variety of Fe concentrations between 43 - 75 % by mass found in individual particles. Other heavy metals, such as Cu, Cr, Mn and Zn, were also found and a high contribution of wear from the brake disc was noticeable, based on the elemental composition. Fe emission factors calculated from the WLTP brake cycle were 8-9 times higher than previously reported values in literature, while Cu levels were significantly lower based on recent trends in brake pad formulations. Four different PAH were detected even at the relatively low temperatures that are common for the WLTP brake test cycle.
Related Concept Videos
Dry Friction
To illustrate this concept, imagine a wooden crate resting on a rough, non-uniform horizontal surface. When an external force is applied to...
Rolling Resistance
For instance, imagine a hard cylinder rolling on a comparatively soft surface. The cylinder's weight compresses the surface beneath it. As the cylinder moves, the material in front of it slows down...
Characteristics of Dry Friction
Before the wheelbarrow starts moving, the static frictional force acts tangentially to the contact surface, opposing the force that is about to induce the motion. This frictional force prevents the...
Journal Bearings
To better understand the concept of journal bearings, consider a rope winch with dry or...

